Six suburban residents were among 21 people sentenced in Houston, Texas, to federal prison terms ranging from two to 20 years after pleading guilty to participating in a “massive” India-based fraud and money laundering scam.

Authorities said thousands of U.S. residents were bilked out of hundreds of millions of dollars.

Among those sentenced last week and earlier:

• Miteshkumar Patel, 42, of Willowbrook, was sentenced to 20 years in prison for money laundering conspiracy. Federal prosecutors say he laundered between $9.5 and $25 million as part of the scheme in which he managed a Chicago-based crew of “runners” who liquidated and laundered proceeds generated through telefraud at India-based call centers.

• Hardik Patel, 31, of Arlington Heights, was sentenced to about 15½ years in prison for wire fraud conspiracy involving the laundering of $3.5 million to $9.5 million, prosecutors said. They say he co-owned and managed an India-based call center involved in the scam, processed payments and kept the books for various call centers involved in the fraud.

• Montu Barot, 30, of Glendale Heights, was sentenced to five years and three months for conspiracy and will be deported to India after he completes his sentence.

• Bharatkumar Patel, 43, of Midlothian, was sentenced to a little more than four years in prison for money laundering conspiracy and will be deported to India after he completes his sentence.

• Rajubhai Patel, 32, of Willowbrook, was sentenced to nearly 12½ years in prison for money laundering conspiracy.

• Asmitaben Patel, 34, of Willowbrook, was sentenced March 23 to two years in prison for conspiracy to commit fraud and money laundering.

• Dipakkumar Patel, 38, also of Illinois, was sentenced by a Georgia federal judge Feb. 14 to four years and three months in prison in exchange for pleading guilty to conspiracy and passport fraud. He was also ordered to pay $128,006.26 in restitution.

Hoffman Estates and Naperville police departments and U.S. Attorneys for Illinois’ Northern District participated in the investigation, according to authorities.

A total of 24 people have been convicted this year for their involvement in the scheme which unfolded between 2012 and 2016, federal prosecutors said.

Using information obtained from data brokers, operators at call centers in Ahmedabad, India, impersonated Internal Revenue Service and U.S. Citizenship and Immigration Service employees. The operators tricked victims into believing they owed the U.S. government money and threatened them with fines, deportation and imprisonment if they did not pay, prosecutors said.

The scammers instructed victims to wire money or purchase stored value cards, which are payment cards with a specific amount of money stored on them. After the victim paid, a network of runners based in the United States laundered the extorted funds through wire transfers or by purchasing reloadable cards. The runners subsequently used the stored value cards to purchase money orders. which they deposited into bank accounts belonging to other people, authorities said.

“These con artists are finally headed to prison,” said U.S. Attorney Ryan Patrick of the Southern District of Texas in a prepared statement. “Their cruel tactics preyed on some very vulnerable people, thereby stealing millions from them.”

Also charged with conspiracy, wire fraud and money laundering are 32 India-based conspirators and five India-based call centers, authorities said.